Serenity Caldwell has a great write up of some of the new watchOS 4 features, and it reminded me that I've developed quite a few gripes about the watchOS 4 beta on my older (Day 1) Series 0 watch.
Frankly it has, for all intents and purposes, become absolutely useless for any real interaction. Still does fine as an Activity Monitor, and notifications usually come through fine, but if I ever actually try to use it for anything it just can't keep up with my touches. I still try every now and then to use it for Siri, the Home app, skipping podcasts in Overcast, checking the weather, etc, and everytime I end up just staring at the spinner waiting for the app to launch. It never does.
My fiancée has been really relunctant about embracing my switch to HomeKit around our apartment. While she still carries around her house keys I don't, since I can just ask Siri to open the doors. Over the weekend she was washing her car outside and took her keys. I went out to give her something, but before I left the apartment I made sure that I had an Apple device on me so I could get back inside (not usually a problem.) My phone was dead, my iPad was playing podcasts on the table, but I had my Apple Watch. I figured I'd be fine, it'd be a bit slow to register with Siri but it would still unlock my door and I'd be back to playing Zelda.
When I walked back to my apartment door I brought up my watch to get Siri up. The watch crashed and I saw that Apple logo, indicating that it was booting up. I tried yelling through the door to tell Siri to unlock it, but thankfully that didn't work. I ended up waiting 10 minutes for my watch to reboot so I could get back inside my house, but finally I just gave up and went back outside to get the keys from Rosalee.
Again, I'm not sure if the problem is more the beta or the device. I haven't had nearly as much trouble with the iOS betas, but watchOS is usually much less stable than iOS anyway. On the other hand this device is approaching 2.5 years old, and honestly the Series 3 can't come soon enough.